Narrative:

We were cleared into position and hold on runway 30 awaiting landing traffic on runway 1L. Saw traffic pass over our departure runway, several seconds later we received our takeoff clearance. WX was VMC with winds at 300 degrees 12 KTS. Because of the low level of the landing traffic, we didn't think wake turbulence would be a factor. We completed before takeoff checklist and initiated our takeoff roll. At approximately 90-100 KTS we received a severe jolt to the aircraft, a cas message that said elevator disconnect with aural warning, I then received an 'abort-abort' call from my first officer and initiated a normal abort takeoff procedure. We then informed tower of the aborted takeoff and proceeded back to the gate. Estimated time from landing traffic/takeoff clearance to time of encounter 30-40 seconds. Because of proximity of landing traffic to the ground, we surmised that wake turbulence shouldn't be a factor. Recommend that time separation be enforced for takeoff procedure on runway 30 with landing traffic on runway 1L at iad. Callback conversation with reporter revealed the following information: after receiving the severe jolt during takeoff, the cas (caution advisory service) light on the MFDU (multi- function display unit) illuminated accompanied by an aural warning. The warning light indicated 'elevator disconnect.' takeoff was aborted. Captain reporter says the jolt felt like a large hammer hitting the aircraft. Reporter says that the only possible cause of the elevator disconnect was the wake of the landing B757 drifting into their flight path. When the elevator disconnected, the only way to reconnect it was by mechanics. Reporter's company contacted dornier whose engineers said it was impossible for a wake to cause the disconnect. Reporter contacted iad tower chief who said they will change their procedures for takeoffs behind B757's.

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Original NASA ASRS Text

Title: TKOF ROLL, 100 KTS, ACFT RECEIVED SEVERE JOLT ATTRIBUTED TO PREVIOUSLY LNDG B757 WAKE. AURAL WARNING AND WARNING LIGHT ILLUMINATED, 'ELEVATOR DISCONNECT.' TKOF WAS ABORTED AND ACFT RETURNED TO RAMP FOR REPAIR.

Narrative: WE WERE CLRED INTO POS AND HOLD ON RWY 30 AWAITING LNDG TFC ON RWY 1L. SAW TFC PASS OVER OUR DEP RWY, SEVERAL SECONDS LATER WE RECEIVED OUR TKOF CLRNC. WX WAS VMC WITH WINDS AT 300 DEGS 12 KTS. BECAUSE OF THE LOW LEVEL OF THE LNDG TFC, WE DIDN'T THINK WAKE TURB WOULD BE A FACTOR. WE COMPLETED BEFORE TKOF CHKLIST AND INITIATED OUR TKOF ROLL. AT APPROX 90-100 KTS WE RECEIVED A SEVERE JOLT TO THE ACFT, A CAS MESSAGE THAT SAID ELEVATOR DISCONNECT WITH AURAL WARNING, I THEN RECEIVED AN 'ABORT-ABORT' CALL FROM MY FO AND INITIATED A NORMAL ABORT TKOF PROC. WE THEN INFORMED TWR OF THE ABORTED TKOF AND PROCEEDED BACK TO THE GATE. ESTIMATED TIME FROM LNDG TFC/TKOF CLRNC TO TIME OF ENCOUNTER 30-40 SECONDS. BECAUSE OF PROX OF LNDG TFC TO THE GND, WE SURMISED THAT WAKE TURB SHOULDN'T BE A FACTOR. RECOMMEND THAT TIME SEPARATION BE ENFORCED FOR TKOF PROC ON RWY 30 WITH LNDG TFC ON RWY 1L AT IAD. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: AFTER RECEIVING THE SEVERE JOLT DURING TKOF, THE CAS (CAUTION ADVISORY SVC) LIGHT ON THE MFDU (MULTI- FUNCTION DISPLAY UNIT) ILLUMINATED ACCOMPANIED BY AN AURAL WARNING. THE WARNING LIGHT INDICATED 'ELEVATOR DISCONNECT.' TKOF WAS ABORTED. CAPT RPTR SAYS THE JOLT FELT LIKE A LARGE HAMMER HITTING THE ACFT. RPTR SAYS THAT THE ONLY POSSIBLE CAUSE OF THE ELEVATOR DISCONNECT WAS THE WAKE OF THE LNDG B757 DRIFTING INTO THEIR FLT PATH. WHEN THE ELEVATOR DISCONNECTED, THE ONLY WAY TO RECONNECT IT WAS BY MECHS. RPTR'S COMPANY CONTACTED DORNIER WHOSE ENGINEERS SAID IT WAS IMPOSSIBLE FOR A WAKE TO CAUSE THE DISCONNECT. RPTR CONTACTED IAD TWR CHIEF WHO SAID THEY WILL CHANGE THEIR PROCS FOR TKOFS BEHIND B757'S.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.